This invention relates particularly to attached-lid security containers of the type shown in U.S. Pat. No. 4,161,261, issued July 17, 1979, to Frater for "Security Container," but it is also applicable to other containers or items utilizing closable lid sections.
Attached-lid security containers are used, for example, in various materials handling applications. They are preferably stackable and nestable, and are now generally of molded plastic construction. The security and strength of the lid closure are important to protect the contents, prevent unauthorized entry, and prevent collapse when a number of containers are stacked or other heavy weights are applied, as when a user stands or places heavy items on the closed lid. The construction in aforesaid U.S. Pat. No. 4,161,261 provides half-length overlapping areas for improved strength and security. In addition, there are projections on the undersides of upper areas that are received through openings in facing lower areas to limit transverse spreading that could otherwise result from deflection when forces are applied to the top of the closed lid, and this further enhances the strength and security of the construction. This arrangement is quite satisfactory, but the present invention provides even greater strength and security.
Another relevant type of lid arrangement is shown in U.S. Pat. No. 3,463,345, issued Aug. 26, 1969, to Bockenstette for "Lidded Tote Box." This patent shows lid sections with a series of raised teeth that interfit with complementary teeth on the other lid section and rest on depressed areas therebetween, and the present invention is also applicable to interfitting lids of this type. In one known toothed construction, the teeth are provided with peripheral vertical reinforcing flanges, and generally transverse portions of the flanges are provided with cross notches that receive upstanding lugs in the depressed areas to limit transverse separation. This arrangement is not totally effective, however, because the notches weaken the flanges and the engagement with the lug is against the end of the relatively narrow flange, which could result in the flange being sheared or broken away.